Our inner world creates our outer world. Our thoughts create our reality, we buy into what we think and believe in. If we are filled with upsets and trauma, resentment and regrets, then the energies we put "out there" into the world are negative. However if we are filled with happiness and joy, appreciation and gratefulness, then the energies become positive.
Since like attracts like.
Full moon is a precious time to reflect on where your life is at this point in time. Allow everything to rise up the surface, using the light of the moon to shine on the darkest areas in your life that may no longer serve and support you - a perfect time to release all the negative energies.